How Hydro Works

1. In order to convert the potential energy of water to electricity, waterpower facilities use either a natural drop in elevation like at Niagara Falls, or create a drop using dams.
2. The amount of electricity generated depends on the vertical distance the water falls and the volume of water.
3. Water from the river or reservoir behind the dam, flows in through an opening called the intake.
4. From the intake, water flows under pressure through a pipe called the penstock.
5. At the end of the penstock a turbine is located. The force of the water turns the blades of the turbine which then turns the shaft inside the turbine.
6. The shaft inside the turbine is connected to a generator, which generates electricity.
7. Once the water passes the turbine it flows through a draft tube out of the station and back into the river.

Source: Primer on the Technologies of Renewable Energy

Pumped Storage 

This technology uses a combination pumps/turbines to pump water from a lower reservoir to an upper reservoir for storage, and generates electricity as the water is released to a lower reservoir. The technology is similar to that used in standard hydro projects except that it uses the combination pumps/turbines to recycle water between the lower and upper reservoirs. This action repeats itself daily and sometimes even several times during a day. Pumped storage effectively works like a very large storage battery, with the elevated water acting as the source of stored energy.

Pumped storage can serve as a peaking plant by generating electricity when prices are high (typically during the day) and consuming electricity to drive the pump when prices are low. It can be also used to respond to short-term fluctuations in electricity demand/supply balance or stabilize the electrical grid. Aside from the ability to time-shift the generation of available power from other projects or nuclear facilities, pumped storage enables rapid responses to requests for generation and can be used to smooth intermittent energy delivery from sources such as wind and solar.

Pumped Storage Video - Statkraft

Links

• Pollution Probe - Primer on the Technologies of Renewable Energy (PDF - Size: 6 Mb)
• British Hydropower Association - Hydro Basics
• Ontario Power Generation - How Hydroelectric Generation Works
• Foundation for Water & Energy Education - Walk Through a Hydroelectric Project